Additives for self-regeneration of epoxy-based coatings

a technology of epoxy-based coatings and additives, applied in coatings, inks, applications, etc., can solve the problems of low mechanical strength of coatings, damage caused by mechanical action, and difficulty in protecting microcapsules, so as to prevent corrosion propagation, ensure the integrity of microcapsules, and promote stability

Inactive Publication Date: 2015-07-02
UNIV DE SAO PAULO +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The patent text describes a special coating that can protect metal surfaces from corrosion. The coating is made with a special epoxy-based material that can self-repair any damage that might occur during use. This is possible because the coating contains microcapsules that can release repairing agents when the coating is cracked or scratched. The microcapsules are added in a special dispersion, which helps to keep the microcapsules stable for a longer period of time, up to a few months. This means that the microcapsules can be prepared and stored without needing to use them right away. Overall, this special coating can provide better protection against corrosion and minimize the need for frequent maintenance.

Problems solved by technology

Although epoxy-based coatings have an excellent performance as corrosion resistant coatings, such coatings still present the inconvenience of a low mechanical strength.
Damages caused by mechanical action can give origin to localized corrosion on metal surfaces exposed by scratches and cracks.
Although useful in controlling corrosion, powder coatings, and consequently the microcapsules, are difficult to apply on surfaces to be protected (coating deposition by heat or electrostatic action).
Although such coatings are able to self-regenerate, the microcapsules dispersed in it are highly unstable in solvents used in known commercial coatings.

Method used

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  • Additives for self-regeneration of epoxy-based coatings
  • Additives for self-regeneration of epoxy-based coatings
  • Additives for self-regeneration of epoxy-based coatings

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0028]The following example illustrates the preparation of the preparation of microcapsules containing linseed oil as repairing agent in concentrations between 10% to 15% by weight, additived with drying agents, using acacia gum as surfactant in a concentration in the range of 0.1% to 0.5% by weight.

[0029]In a beaker, the repairing agent, water and surfactant are added, controlling speed of agitation in the range of 800 rpm to 3000 rpm during the formation of the emulsion to ensure the stability of the emulsion and to provide constant medium homogenization.

[0030]In a later step, after the addition of monomers and hardening agents, the agitation speed is reduced to the range of 100 rpm to 500 rpm so as to facilitate polymerization and to obtain uniform microcapsules.

[0031]Table 1 below illustrates a possible composition of the additives described in this invention.

TABLE 1COMPONENTRange % (by weight)Urea1-3Formaldehyde 37 m %3-5Ammonium chloride0.1-0.2Resorcinols0.1-0.2Sodium chloride...

example 2

[0032]The following example illustrates the stability of additives composed of microcapsules containing the repairing agent when dispersed in an organic solvent, specifically a commercial solvent for high solids content epoxy based corrosion resistant coatings in liquid form.

[0033]Microcapsules prepared in accordance with the method described in example 1 were dispersed in solvent thus obtaining a fully stable dispersion, in that the integrity of the microcapsules is maintained during application, a very important parameter to avoid migration of the repairing agent through their walls.

[0034]FIG. 3 illustrates the obtained dispersion containing 60% of microcapsules and 40% of paint solvent after one day of preparation (FIG. 3A) and after fifteen days (FIG. 3B) of conditioning in wet film, showing good dispersion stability. The dispersion stability is very important for use in paints with high solids content.

example 3

[0035]The following example illustrates the use of additives prepared according to example 2 in the formulation of high solids content epoxy based corrosion resistant coatings in liquid form.

[0036]From the dispersion containing the microcapsules obtained according to example 2 and the addition of those at a concentration of 5% to 20% (by weight) in wet base to high solids content epoxy based corrosion resistant coatings in liquid form; specimens were painted with a thickness in the range of 500 microns, using different dispersion / solvent mix compositions whose dry layer thickness and quantity of capsules in wet base are illustrated in Table 2 below.

TABLE 2Amount ofAmount of wetdispersion (capsule +based capsulesDry layerSpecimensolvent) % (m / m)% (m / m)thickness μmCp100477 ± 19Cp2106.4478 ± 25Cp32012.8491 ± 27

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Abstract

Additives are described for use in high solids content epoxy-based corrosion resistant coatings in liquid form, where such additives are composed by microcapsules containing a regenerating agent dispersed in an organic solvent.The coatings, when additivated with such dispersion, will have the ability to self-regenerate in the event of damages (cracks or scratches) to the applied and cured coating on the metal surface, preventing the propagation of corrosion on the exposed metal surface.

Description

BACKGROUND OF THE INVENTION[0001]The present invention refers to additives for epoxy-based corrosion resistant coatings, more specifically to additives prepared from the dispersion of microcapsules containing repairing agents in organic solvents. Such additives, when added in liquid form to epoxy-based corrosion resistant coatings, are able to promote coating self-regeneration, after cure, particularly in situations of damage to the coating (cracks or scratches). The coating self-regeneration occurs due to the release of repairing agents contained in the microcapsules-agents that form a new protective coating over the damage, preventing corrosion propagation on the exposed surface.DESCRIPTION OF RELATED ART[0002]In the oil industry the corrosion of metal pipelines and fuel storage systems is a permanent concern for operators and engineers. One of the ways to minimize corrosion in refineries and oil exploration and production units is to use corrosion resistant coatings.[0003]Among t...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08G12/12C08L63/00C08K5/103C09D7/63
CPCC08G12/12C08L63/00C08K5/103C09D7/70C09D5/08C09D163/00C08K5/101C08K9/10C08G14/08C08L61/34C09D7/63C08L61/24
Inventor GRINAPEL LACHTERMACHER, MARLYPEREIRA COELHO, JORGE FERNANDOKOEBSCH, ANDREALTOE FERREIRA, PEDROSOLYMOSSY, VICTORVIEIRA AOKI, IDALINA
Owner UNIV DE SAO PAULO
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